DS1321
Flexible Nonvolatile Controller with
Lithium Battery Monitor
www.dalsemi.com
FEATURES
Converts CMOS SRAM into nonvolatile
memory
Unconditionally write-protects SRAM when
V
CC
is out of tolerance
Automatically switches to battery backup
supply when V
CC
power failure occurs
Flexible memory organization
- Mode 0: 4 banks with 1 SRAM each
- Mode 1: 2 banks with 2 SRAMs each
- Mode 2: 1 bank with 4 SRAMs each
Monitors voltage of a lithium cell and
provides advanced warning of impending
battery failure
Signals low-battery condition on active low
Battery Warning output signal
Resets processor when power failure occurs
and holds processor in reset during system
power-up
Optional -5% or -10% power-fail detection
16-pin DIP, 16-pin SOIC and 20-pin TSSOP
packages
Industrial temperature range of -40°C to
+85°C
PIN ASSIGNMENT
V
CCO
V
BAT
TOL
CEI1
CEI2
A/CEI3
B/CEI4
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
CCI
RST
BW
CEO1
CEO2
CEO3
CEO4
MODE
DS1321 16-Pin DIP
(300-mil)
V
CCO
V
BAT
TOL
CEI1
CEI2
A/CEI3
B/CEI4
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
CCI
RST
BW
CEO1
CEO2
CEO3
CEO4
MODE
DS1321S 16-Pin SOIC
(150-mil)
PIN DESCRIPTION
V
CCI
V
CCO
V
BAT
A, B
- +5V Power Supply Input
- SRAM Power Supply Output
- Backup Battery Input
- Address Inputs
CEI1
-
CEI4
- Chip Enable Inputs
CEO1
-
CEO4
- Chip Enable Outputs
TOL
- V
CC
Tolerance Select
BW
- Battery Warning Output (Open
Drain)
RST
- Reset Output (Open Drain)
MODE
- Mode Input
GND
- Ground
NC
- No Connection
V
CCO
V
BAT
TOL
CEI1
CEI2
NC
A/CEI3
B/CEI4
NC
GND
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
V
CCI
RST
BW
CEO1
CEO2
NC
CEO3
CEO4
NC
MODE
DS1321E 20-Pin TSSOP
1 of 12
111999
DALLAS [ DALLAS SEMICONDUCTOR ]
